During exploration of extraterrestrial space (e.g., outer space, the moon, other planets, etc.), people and/or instruments are carried by spacecraft into space, and may be transferred from a spacecraft to a space module such as, for example, a space station, a lunar station, or a planetary station. As used herein, the term “spacecraft” means and includes a vehicle or device designed for travel or operation outside the earth's atmosphere. Thus, spacecraft include both vehicles designed for propulsion through space, as well as station modules to be transported, located and used in extraterrestrial settings.
On earth, the atmosphere provides at least some degree of protection from harmful radiation (e.g., cosmic rays and solar radiation) and micrometeoroid impacts (i.e., micrometeorites). Radiation and micrometeoroids can be harmful to people, and can damage instruments and equipment used for exploration of extraterrestrial space. In extraterrestrial settings, a protective atmosphere like that found on earth is not present. Thus, people and instruments in extraterrestrial settings need to be shielded from such radiation and micrometeoroid impacts. Radiation shields are used on spacecraft to shield people and/or instruments from harmful radiation and micrometeorites.
Previous designs have made use of metallic material alloys, mostly of aluminum, for spacecraft designs. More recent studies have discussed the use of polyethylene in spacecraft, but polyethylene alone has insufficient structural properties. There has been resistance by customers within the industry to adopt primary composite structures on man-rated spacecraft until problems with radiation shielding, and with structural and fracture mechanics issues, have been adequately addressed.